LC-MS/MS Method for the Determination of HCTZ and Losartan from Human Plasma Using SOLA CX

Importance of the Topic

The ability to quantify hydrochlorothiazide (HCTZ) and losartan in human plasma is critical for therapeutic monitoring, pharmacokinetic studies and quality control in clinical and bioanalytical laboratories. Fast, reliable methods with minimal sample volume and solvent consumption support high throughput workflows and help ensure data accuracy in drug development and patient care.

Objectives and Article Overview

This application note describes the development and validation of a rapid LC-MS/MS method for simultaneous determination of HCTZ and losartan in human plasma. Key goals include demonstrating the performance benefits of Thermo Scientific SOLA CX solid phase extraction cartridges coupled with an Accucore aQ column, achieving separation in under two minutes with high reproducibility, sensitivity and minimal solvent use.

Methodology and Instrumentation

The sample preparation workflow uses SOLA CX cartridges to process 100 µL of spiked plasma. After conditioning with methanol and water, samples are loaded, washed with acidified water and eluted with acetonitrile/ammonia. Eluates are dried and reconstituted in 80:20 water:acetonitrile.

Instrumentation Used

• Thermo Scientific SOLA CX SPE cartridges (10 mg/1 mL) and positive-pressure manifold
• Thermo Scientific Accela 600 HPLC system
• Accucore aQ column (50 × 2.1 mm, 2.6 µm)
• Thermo Scientific TSQ Vantage triple quadrupole mass spectrometer with HESI source

Main Results and Discussion

The method provided linear calibration from 0.5 to 500 ng/mL for both analytes, with correlation coefficients of 0.9974 (HCTZ) and 0.9956 (losartan). Precision (RSD) was below 3.5% for HCTZ and below 6.5% for losartan at low (1.5 ng/mL) and high (400 ng/mL) QC levels. Mean recoveries were 86.4% for HCTZ and 65.8% for losartan. Negligible carryover was observed for HCTZ; two blank injections were required to eliminate losartan carryover after the highest standard.

Benefits and Practical Applications

• High throughput: two-minute run time accelerates sample analysis.
• Reduced solvent and sample requirements: minimizes costs and waste.
• Robust SPE cleanup: improved reproducibility and extract cleanliness.
• Sensitive and accurate quantification: suitable for therapeutic drug monitoring.

Future Trends and Potential Applications

Advances may include automation of SPE workflows, integration with microflow LC-MS for reduced solvent use, and application to a broader range of polar pharmaceuticals and metabolites. Improved cartridge chemistries could further enhance extract purity and throughput for large-scale clinical studies.

Conclusion

The combination of SOLA CX cartridges and an Accucore aQ column delivers a fast, reliable and cost-effective LC-MS/MS method for determining HCTZ and losartan in human plasma. The protocol meets stringent criteria for linearity, accuracy, precision and throughput, making it a robust tool for bioanalytical laboratories.

Reference

• Jones J, Phipps K. LC-MS/MS Method for the Determination of HCTZ and Losartan from Human Plasma Using SOLA CX. Thermo Fisher Scientific Application Note ANCCSSOLAHZ&LN. 2011.